Field Response of Brassica Germplasm against Alternaria Leaf Spot Disease and its Management

Brassica is an edible oilseed crop and world’s third most important oilseed source. Alternaria leaf spot disease of Brassica, caused by Alternaria brassicae (Berk) is major limiting factor for its yield loss. In current study forty-two Brassica germplasm (B. napus = 17, B. juncea = 25) were evaluated against Alternaria leaf spot disease at research area of Plant Pathology Research Institute (PPRI), Ayub Agricultural Research Institute (AARI), Faisalabad, Pakistan. These germplasms were sown in augmented design with 10 cm plant x plant and 60 cm row x row distance in single replication. A susceptible check KJ-159 was sown after every two entries. Data were recorded on 0-9 disease severity rating scale. Out of 17 germplasm of B. napus no germplasm was found to be immune. Two germplasm exhibited highly resistant while eight germplasm showed resistance response against the disease. Six germplasm were moderately resistant and only one showed moderately susceptible response. Similarly, out of 25 germplasm of B. junceas even were found moderately resistant and ten showed moderately susceptible response. Seven were susceptible while only one germplasm was highly susceptible. Then in-vitro efficacy of different fungicides was evaluated against A. brassicae. For evaluation of fungicides Potato Dextrose Agar (PDA) amended with five different fungicides at different concentrations (10, 50, 100 and 200 ppm) was used. Experiment was conducted in completely randomized design with ten replications. Data were recorded on mycelial growth (mm) of fungus. Mancozeb (Ethylene bisdithiocarbamate) and Nativo (Tebuconazole) significantly inhibited the growth at all concentrations while Antracol (Propineb) was significantly least effective against A. brassicae. The current research provided the new resistance source of Brassica germplasm to the breeders against Alternaria leaf spot disease and its management.